The parents of Harry Dunn have expressed frustration that the Crown Prosecution Service (CPS) is yet to make a charging decision over the US suspect in the case.

Tim Dunn and Charlotte Charles have said they are “absolutely on (their) knees” as a family almost 12 weeks since 19-year-old Mr Dunn died in a head-on collision.

Anne Sacoolas, the wife of an American intelligence officer, is believed to have been driving on the wrong side of the road when she hit Mr Dunn’s motorbike outside RAF Croughton on August 27.

Mrs Sacoolas claimed diplomatic immunity after the incident and returned to the US, sparking an international controversy.

Harry Dunn, pictured in January 2014, with his newborn niece Lola Harber (Family Handout/PA)
Harry Dunn, pictured in January 2014, with his newborn niece Lola Harber (Family Handout/PA)

Earlier this month, Northamptonshire Police – who were not told Mrs Sacoolas had left the UK – handed a file of evidence to the CPS after conducting an interview with the 42-year-old in the US.

The family said they were “strongly” led to believe that they could expect a charging decision this week following discussions between their spokesman Radd Seiger and Chief Constable Nick Adderley.

But in a statement released on Friday, Mr Dunn’s parents said the Chief Constable had told Mr Seiger there had been no decision and that a timeline of when to expect one had not been set out.

“We are absolutely on our knees as a set of parents and a family,” Mr Dunn and Mrs Charles said.

“We lost our beautiful boy almost 12 weeks ago and the authorities are making our lives a living hell.”

Mr Dunn's family at a press conference in New York (Josh Payne/PA)
Mr Dunn’s family at a press conference in New York (Josh Payne/PA)

Mr Dunn’s parents accused authorities of mistreating and lying to them, adding: “We really suspect that something funny is going on.”

In the statement, Mr Seiger said he had learned from police that the CPS had been liaising with the Foreign Office (FCO) and “working through the diplomatic immunity position”.

He referred to Foreign Secretary Dominic Raab telling the Commons that the UK Government believed diplomatic immunity “clearly ended” for Mrs Sacoolas when she left the country.

He said he and the Dunn family were “at a complete loss to understand why there should be any interaction between the FCO and the CPS”.

The 19-year-old’s family have been fighting for action in a three-month saga that saw the case taken to the White House.

A CPS spokesperson said: “We fully understand how difficult this must be for Harry Dunn’s family, and the CPS is doing everything possible to reach a charging decision as soon as we can.

“Unfortunately, we are unable to tell the family how long that will take. Each case is different, and the CPS has a duty to carefully consider all the available information, in order to make an independent and objective decision.”

The FCO have been contacted for comment.